1. Field of the Invention
The present invention relates to a system for assessing movement and agility skills and, in particular, to a wireless position tracker for continuously tracking and determining player position during movement in a defined physical space through player interaction with tasks displayed in a computer generated,                specially translated virtual space for the quantification of the player's movement and agility skills based on time and distance traveled in the defined physical space.        
2. The Related Art
Sports specific skills can be classified into two general conditions:                1) Skills involving control of the body independent from other players; and        2) Skills including reactions to other players in the sports activity.The former includes posture and balance control, agility, power and coordination. These skills are most obvious in sports such as volleyball, baseball, gymnastics, and track and field that demand high performance from an individual participant who is free to move without opposition from a defensive player. The latter encompasses interaction with another player-participant. This includes various offense-defense situations, such as those that occur in football, basketball, soccer, etc.        
Valid testing and training of sport-specific skills requires that the player be challenged by unplanned cues which prompt player movement over distances and directions representative of actual game play. The players optimum movement path should be selected based on visual assessment of his or her spatial relationship with opposing players and/or game objective. A realistic simulation must include a sports relevant environment. Test methods prompting, the player to move to fixed ground locations are considered artificial. Nor are test methods employing static or singular movement cues such as a light or a sound consistent with accurate simulations of actual competition in many sports.
To date, no accurate, real time model of the complex, constantly changing, interactive relationship between offensive and defensive opponents engaging in actual competition exists. Accurate and valid quantification of sport-specific movement capabilities necessitates a simulation having fidelity with real world events.
At the most primary level, sports such as basketball, football and soccer can be characterized by the moment to moment interaction between competitors in their respective offensive and defensive roles. It is the mission of the player assuming the defensive role to “contain”, “guard”, or neutralize the offensive opponent by establishing and maintaining a real-time synchronous relationship with the opponent. For example, in basketball, the defensive player attempts to continually impede the offensive player's attempts to drive to the basket by blocking with his or her body the offensive player's chosen path, while in soccer the player controlling the ball must maneuver the ball around opposing players.
The offensive player's mission is to create a brief asynchronous event, perhaps of only a few hundred milliseconds in duration, so that the defensive player's movement is no longer in “phase” with the offensive player's. During this asynchronous event, the defensive player's movement no longer mirrors, i.e., is no longer synchronous with, his or her offensive opponent. At that moment, the defensive player is literally “out of position” and therefore is in a precarious position, thereby enhancing the offensive player's chances of scoring. The offensive player can create an asynchronous event in a number of ways. The offensive player can “fake out” or deceive his or her opponent by delivering purposefully misleading information as to his or her immediate intentions. Or the offensive player can “overwhelm” his opponent by abruptly accelerating the pace of the action to levels exceeding the defensive player's movement capabilities.
To remain in close proximity to an offensive opponent, the defensive player must continually anticipate or “read” the offensive player's intentions. An adept defensive player will anticipate the offensive player's strategy or reduce the offensive player's options to those that can easily be contained. This must occur despite the offensive players attempts to disguise his or her actual intentions with purposely deceptive and unpredictable behavior. In addition to being able to “read”, i.e., quickly perceive and interpret the intentions of the offensive player, the defensive player must also possess adequate sport-specific movement skills to establish and maintain the desired (from the perspective of the defensive player) synchronous spatial relationship.
These player-to-player interactions are characterized by a continual barrage of useful and purposefully misleading visual cues offered by the offensive player and constant reaction and maneuvering by the defensive participant. Not only does the defensive player need to successfully interpret visual cues “offered” by the offensive player, but the offensive player must also adeptly interpret visual cues as they relate to the defensive player's commitment, balance and strategy. Each player draws from a repertoire of movement skills which includes balance and postural control, the ability to anticipate defensive responses, the ability to generate powerful, rapid, coordinated movements, and reaction times that exceed that of the opponent. These sport-specific movement skills are often described as the functional or motor related components of physical fitness.
The interaction between competitors frequently appears almost chaotic, and certainly staccato, as a result of the “dueling” for advantage. The continual abrupt, unplanned changes in direction necessitate that the defensive player maintain control over his or her center of gravity throughout all phases of movement to avoid over committing. Consequently, movements of only fractions of a single step are common for both the defensive and offensive players. Such abbreviated movements insure that peak or high average velocities are seldom, if ever, achieved. Accordingly, peak acceleration and power are more sensitive measures of performance in the aforementioned scenario. Peak acceleration of the center of mass can be achieved more rapidly than peak velocity, often in one step or less, while power can relate the acceleration over a time interval, making comparisons between players more meaningful.
At a secondary level, all sports situations include decision-making skills and the ability to focus on the task at hand. The present invention simulation trains participants in these critical skills. Therefore, athletes learn to be “smarter” players due to increased attentional skills, intuition, and critical, sports related reasoning.
Only through actual game play, or truly accurate simulation of game play, can the ability to correctly interpret and respond to sport specific visual cues be honed. The same requirement applies to the refinement of the sport-specific components of physical fitness that is essential for adept defensive and offensive play. These sport-specific components include reaction time, balance, stability, agility and first step quickness.
Through task-specific practice, athletes learn to successfully respond to situational uncertainties. Such uncertainties can be as fundamental as the timing of the starter's pistol, or as complex as detecting and interpreting continually changing, “analog” stimuli presented by an opponent. To be task-specific, the type of cues delivered to the player must simulate those experienced in the players sport. Task-specific cuing can be characterized, for the purposes of this document, as either dynamic or static.
Dynamic cuing delivers continual, “analog” feedback to the player by being responsive to, and interactive with, the player. Dynamic cuing is relevant to sports where the player must possess the ability to “read” and interpret “telegraphing” kinematic detail in his or her opponent's activities. Players must also respond to environmental cues such as predicting the path of a ball or projectile for the purposes of intercepting or avoiding it. In contrast, static cuing is typically a single discreet event, and is sport relevant in sports such a track and field or swimming events. Static cues require little cerebral processing and do not contribute to an accurate model of sports where there is continuous flow of stimuli necessitating sequential, real time responses by the player. At this level, the relevant functional skill is reaction time, which can be readily enhanced by the present invention's simulation.
In sports science and coaching, numerous tests of movement capabilities and reaction time are employed. However, these do not subject the player to the type and frequency of sport-specific dynamic cues requisite to creating an accurate analog of actual sports competition described above.
For example, measures of straight-ahead speed such as the 100-meter and 40 yard dash only subject the player to one static cue, i.e, the sound of the gun at the starting line. Although the test does measure a combination of reaction time and speed, it is applicable to only one specific situation (running on a track) and, as such, is more of a measurement of capacity, not skill. In contrast, the player in many other sports, whether in a defensive or offensive role, is continually bombarded with cues that provide both useful and purposely misleading information as to the opponents immediate intentions. These dynamic cues necessitate constant, real time changes in the player's movement path and velocity; such continual real-time adjustments preclude a player from reaching maximum high speeds as in a 100-meter dash. Responding successfully to dynamic cues places constant demand on a player's agility and the ability to assess or read the opposing player intentions.
There is another factor in creating an accurate analog of sports competition. Frequently, a decisive or pivotal event such as the creation of an asynchronous event does not occur from a preceding static or stationary position by the players. For example, a decisive event most frequently occurs while the offensive player is already moving and creates a phase shift by accelerating the pace or an abrupt change in direction. Consequently, it is believed that the most sensitive indicators of athletic prowess occur during abrupt changes in vector direction or pace of movement from “preexisting movement”. All known test methods are believed to be incapable of making meaningful measurements during these periods.
Known in the art are various types of virtual reality or quasi virtual reality systems used for entertainment purposes or for measuring physical exertion. Examples of such systems are U.S. Pat. No. 5,616,078, to Oh, entitled “Motion-Controlled Video Entertainment System”; U.S. Pat. No. 5,423,554, to Davis, entitled “Virtual Reality Game Method and Apparatus”; U.S. Pat. No. 5,638,300, to Johnson, entitled “Golf Swing Analysis System”: U.S. Pat. No. 5,524,637, to Erickson, entitled “Interactive System for Measuring Physiological Exertion”; U.S. Pat. No. 5,469,740, to French et al., entitled “Interactive Video Testing and Training System”; U.S. Pat. No. 4,751,642, to Silva et al., entitled “Interactive Sports Simulation System with Physiological Sensing and Psychological Conditioning”; U.S. Pat. No. 5,239,463, to Blair et al., entitled “Method and is Apparatus for Player Interaction with Animated Characters and Objects”; and U.S. Pat. No. 5,229,756, to Kosugi et al., entitled “Image Control Apparatus”. These prior art systems lack realism in their presentations and/or provide no measurement or inadequate measurement of physical activity.